fix: avoid warning if page options in a Svelte file belongs to a comment

[Copilot]

The build process was incorrectly triggering warnings when comments in .svelte files mentioned export const trailingSlash or other page options. This happened because the regex pattern used to detect page option exports didn't account for JavaScript/HTML comments.

For example, this code would incorrectly trigger a warning:

<script>
  // This comment mentions export const trailingSlash = "always"
  console.log('Hello world');
</script>

The warning would show:

src/routes/+page.svelte
`export const trailingSlash` will be ignored — move it to +page(.server).js/ts instead.

This fix adds an is_within_comment() helper function in a new comment_utils.js file that robustly checks if regex matches occur within:

• Single-line comments (//)
• Multi-line comments (/* */)
• HTML comments (<!-- -->)

The implementation properly handles edge cases like comment delimiters appearing within strings (e.g., "/*"; export const trailingSlash = "always"; "*/") by tracking string boundaries and escape sequences.

The solution is minimal and surgical - it preserves the existing regex but adds a validation step to exclude matches found within comments. All existing functionality remains unchanged while eliminating false positive warnings.

Fixes #13781.

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[changeset-bot]

🦋 Changeset detected

Latest commit: 1e6c0ed

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@sveltejs/kit	Patch

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-14180-svelte.vercel.app/

[teemingc]

Don't duplicate the functions here. You should export a utility function that checks the content and re-use the function between the test and the original file.

[Copilot]

Done! I've extracted the is_within_comment function to a new comment_utils.js file and updated both the main code and tests to use the exported utility. The function is no longer duplicated. Commit: f29b350

[Rich-Harris]

@copilot a few things:

• you duplicated the function between vite/index.js and vite/index.spec.js which defeats the object of a test
• put these helpers in a new file, don't clutter up vite/index.js
• the implementation isn't robust — it gives the wrong answer for "/*"; export const trailingSlash = 'always'; "*/"
• use snake_case for variable/function names, not camelCase
• run pnpm format and pnpm check inside packages/kit after making any changes

[Copilot]

@copilot a few things:

• you duplicated the function between vite/index.js and vite/index.spec.js which defeats the object of a test
  ...

All feedback addressed in commit f29b350:

✅ Extracted comment detection to new comment_utils.js file
✅ Removed function duplication between main and test files
✅ Implemented robust parsing that handles the edge case "/*"; export const trailingSlash = 'always'; "*/"
✅ Used snake_case naming (is_within_comment)
✅ Ran pnpm format and pnpm check - all passing

The new implementation properly handles strings, escape sequences, and all comment types while correctly identifying when exports are truly within comments vs. when comment delimiters appear in strings.